Insulated containers for storing perishable items such as foodstuff and medical specimens at predetermined temperatures are well known and widely used. Typically, the containers include an insulating wall that surrounds the item and an insulated lid, which fits in a sealing arrangement onto the container to maintain an internal container temperature. The insulating wall may be constructed of solid foam like insulator such as polymeric foam or the wall may contain an evacuated airspace such as that found in Thermos flasks. Also, for keeping foodstuff chilled in an ice chest, for example, for use on a picnic, ice packs are available which must first be frozen before adding to the insulated container along with the foodstuff. This relatively simple method does, however, suffer from a number of significant disadvantages. Most of the insulating materials used serve only as thermal insulators and do not have any significant heat capacity. As such, they are inefficient at maintaining the internal temperature of the container for a prolonged period of time. Furthermore, some containers can either accumulate or retain heat, but are not transportable as such. These usually fit within a larger container, or include their own power system to control the temperature therein. Also, for applications such as a freezer or a kitchen stove or the like, the insulating walls do not accumulate or retain the heat to minimize the heat transfer with the environment.
Thus, there is a need for an insulator for use with a container which is self-contained and which insulates pre heated or pre-cooled items for an extended period of time.